Java中的 Scanner nextLong() 方法和示例

Java.util.Scanner类的nextLong(radix)方法将输入的下一个标记扫描为 long。如果翻译成功，扫描仪会超过匹配的输入。如果未传递参数 radix，则其行为与 nextLong(radix) 类似，其中基数被假定为默认基数。

句法：

public long nextLong()

参数：该函数接受一个参数基数，该基数用于将标记解释为一个长值。

返回值：此函数从输入返回长扫描。

异常：该函数抛出三个异常，如下所述：

InputMismatchException：如果下一个标记与 Integer 正则表达式不匹配，或者超出范围
NoSuchElementException：如果输入用尽则抛出
IllegalStateException：如果此扫描仪关闭则抛出

下面的程序说明了上述函数：

方案一：

// Java program to illustrate the
// nextLong() method of Scanner class in Java
// without parameter
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        String s = "Gfg 9 + 6 = 12.0";
  
        // create a new scanner
        // with the specified String Object
        Scanner scanner = new Scanner(s);
  
        while (scanner.hasNext()) {
  
            // if the next is a Long,
            // print found and the Long
            if (scanner.hasNextLong()) {
                System.out.println("Found Long value :"
                                   + scanner.nextLong());
            }
  
            // if no Long is found,
            // print "Not Found:" and the token
            else {
                System.out.println("Not found Long value :"
                                   + scanner.next());
            }
        }
        scanner.close();
    }
}

输出：

Not found Long value :Gfg
Found Long value :9
Not found Long value :+
Found Long value :6
Not found Long value :=
Not found Long value :12.0

方案二：

// Java program to illustrate the
// nextLong() method of Scanner class in Java
// with parameter
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        String s = "Gfg 9 + 6 = 12.0";
  
        // create a new scanner
        // with the specified String Object
        Scanner scanner = new Scanner(s);
  
        while (scanner.hasNext()) {
  
            // if the next is a Long,
            // print found and the Long
            if (scanner.hasNextLong()) {
                System.out.println("Found Long value :"
                                   + scanner.nextLong(12));
            }
  
            // if no Long is found,
            // print "Not Found:" and the token
            else {
                System.out.println("Not found Long value :"
                                   + scanner.next());
            }
        }
        scanner.close();
    }
}

输出：

Not found Long value :Gfg
Found Long value :9
Not found Long value :+
Found Long value :6
Not found Long value :=
Not found Long value :12.0

程序 3：演示 InputMismatchException

// Java program to illustrate the
// nextLong() method of Scanner class in Java
// InputMismatchException
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        try {
  
            String s = "Gfg 9 + 6 = 12.0";
  
            // create a new scanner
            // with the specified String Object
            Scanner scanner = new Scanner(s);
  
            while (scanner.hasNext()) {
  
                // if the next is a Long,
                // print found and the Long
                // since the value 60 is out of range
                // it throws an exception
  
                System.out.println("Next Long value :"
                                   + scanner.nextLong());
            }
            scanner.close();
        }
        catch (Exception e) {
            System.out.println("Exception thrown: " + e);
        }
    }
}

输出：

Exception thrown: java.util.InputMismatchException

程序 4：演示 NoSuchElementException

// Java program to illustrate the
// nextLong() method of Scanner class in Java
// NoSuchElementException
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        try {
  
            String s = "Gfg";
  
            // create a new scanner
            // with the specified String Object
            Scanner scanner = new Scanner(s);
  
            // Trying to get the next Long value
            // more times than the scanner
            // Hence it will throw exception
            for (int i = 0; i < 5; i++) {
  
                // if the next is a Long,
                // print found and the Long
                if (scanner.hasNextLong()) {
                    System.out.println("Found Long value :"
                                       + scanner.nextLong());
                }
  
                // if no Long is found,
                // print "Not Found:" and the token
                else {
                    System.out.println("Not found Long value :"
                                       + scanner.next());
                }
            }
            scanner.close();
        }
        catch (Exception e) {
            System.out.println("Exception thrown: " + e);
        }
    }
}

输出：

Not found Long value :Gfg
Exception thrown: java.util.NoSuchElementException

程序 5：演示 IllegalStateException

// Java program to illustrate the
// nextLong() method of Scanner class in Java
// IllegalStateException
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        try {
  
            String s = "Gfg 9 + 6 = 12.0";
  
            // create a new scanner
            // with the specified String Object
            Scanner scanner = new Scanner(s);
  
            // close the scanner
            scanner.close();
            System.out.println("Scanner Closed");
  
            System.out.println("Trying to get "
                               + "next Long value");
  
            while (scanner.hasNext()) {
  
                // if the next is a Long,
                // print found and the Long
                if (scanner.hasNextLong()) {
                    System.out.println("Found Long value :"
                                       + scanner.nextLong());
                }
  
                // if no Long is found,
                // print "Not Found:" and the token
                else {
                    System.out.println("Not found Long value :"
                                       + scanner.next());
                }
            }
        }
        catch (Exception e) {
            System.out.println("Exception thrown: " + e);
        }
    }
}

输出：

Scanner Closed
Trying to get next Long value
Exception thrown: java.lang.IllegalStateException: Scanner closed

参考： https: Java/util/Scanner.html#nextLong(int)